Software development lifecycle question

Hi,

I have been reading through the 'Object Oriented Classical Software Engineering' book and doing the chapter questions and I have struggling with a particular question. The question is:

Suppose you have to build a product to determine the inverse of 653.228 to five decimal places. Once the product has been implemented and tested, it will be thrown away. Which life-cycle model would you use? Give reasons for your answer.

Initially, I thought it was the iterative and incremental life cycle, however, after further reading, I am thinking it's the rapid prototyping model.